The new rules, which have been sent to bishops around the world, apply equally to Catholic women who agree to a ceremony of ordination and to the bishop who conducts it. Both would be excommunicated. Since the Vatican does not accept that women can become priests, it does not recognise the outcome of any such ceremony.

The Vatican's reclassification of attempted female ordination was part of a revision of a 2001 decree, the main purpose of which was to tighten up the rules on sex abuse by priests in reaction to the scandals that have been sweeping through the church since January. The most important change is to extend the period during which a clergyman can be tried by a church court from 10 to 20 years, dating from the 18th birthday of his victim.

The new rules introduce speedier procedures for dealing with the most urgent and serious cases; allowed for lay people to form part of church tribunals that judge such cases; put abuse of the mentally disabled on a level with that of minors, and introduced a new crime of paedophile pornography.

The pope's spokesman, Father Federico Lombardi, stressed that the changes applied solely to canon, or church, law. They had no bearing on whether suspected offenders should be reported to the civil authorities.

He said that issue had already been dealt with earlier this year in instructions making it clear to bishops that they must report cases promptly.

The Vatican was working on further instructions "so that the directives it issues on the subject of sexual abuse of minors, either by the clergy or institutions connected with the church, may be increasingly rigorous, coherent and effective," he said.